On board diagnostics (OBD-II)
Your vehicle is equipped with a computer that monitors the engine’s
emission control system. This system is commonly known as the On
Board Diagnostics System (OBD-II). This OBD-II system protects the
environment by ensuring that your vehicle continues to meet
government emission standards. The OBD-II system also assists your
authorized dealer in properly servicing your vehicle. When the
indicator illuminates, the OBD-II system has detected a malfunction.
Temporary malfunctions may cause your
indicator to illuminate.
Examples are:
1. The vehicle has run out of fuel—the engine may misfire or run poorly.
2. Poor fuel quality or water in the fuel.
3. The fuel cap may not have been securely tightened. SeeFuel filler
capin this chapter.
These temporary malfunctions can be corrected by filling the fuel tank
with good quality fuel and/or properly tightening the fuel cap. After three
driving cycles without these or any other temporary malfunctions
present, the
indicator should turn off—A driving cycle consists of a
cold engine startup followed by mixed city/highway driving. No additional
vehicle service is required.
If the
indicator remains on, have your vehicle serviced at the first
available opportunity.
Readiness for Inspection/Maintenance (I/M) testing
In some localities, it may be a legal requirement to pass an I/M test of
the on-board diagnostics system. If your
indicator is on, refer to
the description in theWarning lights and chimessection of the
Instrument Clusterchapter. Your vehicle may not pass the I/M test with
the
indicator on.
If the vehicle’s powertrain system or its battery has just been serviced,
the on-board diagnostics system is reset to a “not ready for I/M test”
condition. To ready the on-board diagnostics system for I/M testing, a
minimum of 30 minutes of city and highway driving is necessary as
described below:
•First, at least 10 minutes of driving on an expressway or highway.
•Next, at least 20 minutes driving in stop-and-go, city-type traffic with
at least four idle periods.
2006 Expedition(exd)
Owners Guide (post-2002-fmt)
USA(fus)
Maintenance and Specifications
334
